1. Field of the Invention
The present invention relates generally to a method of fabricating a semiconductor device, and more particularly, to a method of fabricating a semiconductor device in which a method of forming a bump provided as connecting means on the surface of the semiconductor device is improved.
2. Description of the Related Art
In fabricating a semiconductor device, a bump forming step is carried out after a wiring forming step for forming predetermined wiring and a protective film forming step for forming a protective film on the surface of a semiconductor substrate are terminated.
In the bump forming step, a series of processing such as sputtering, photolithography, plating, resist stripping, etching, and annealing is performed.
Specifically, description is made with reference to FIGS. 1A to 1E.
A TiW barrier layer 3 and an Au seed layer 4 are continuously formed, respectively, by sputtering on an aluminum electrode 2 exposed from a hole la formed in a protective film 1. The barrier layer 3 and the seed layer 4 are formed so as to cover not only the surface of the electrode 2 but also the surface of the protective film 1 (FIG. 1A).
A resist 5 is then formed such that only an upper part of the electrode 2 is exposed by photolithography (FIG. 1B).
After the resist 5 is formed, a bump 6 is provided by plating (FIG. 1C).
After the bump 6 is formed, the resist 5 is stripped (FIG. 1D).
Thereafter, unnecessary parts of the seed layer 4 and the barrier layer 3 are etched away. The surface of the bump 6 is slightly ground as the etching is performed (FIG. 1E). The semiconductor substrate is finally baked by an oven.
In the conventional steps of fabricating the semiconductor device, the bump forming step comprising the series of processing is carried out after the protective film forming step is terminated, as described above. Accordingly, the number of steps of fabricating the semiconductor device is large, so that a time period required for the fabrication is lengthened.